Red algae belonging to the genus Porphyra comprise multiple species including:                Porphyra umbilicalis, collected in Brittany; Porphyra purpurea, present in Brittany; Porphyra tenera, cultivated in Japan; Porphyra yezoensis, cultivated in Japan; and Porphyra columbina, collected in Australia.        
The alimentary species of Porphyra are also called “nori.” The species Porphyra umbilicalis forms a thin orbicular lanceolate lamella of purplish color which can reach 60 cm in length. The Porphyra species are the most widely consumed alimentary algae in the world. In France, the species Porphyra umbilicalis is approved for human alimentary consumption. The nutritional value of this algae stems from its richness in various compounds such as:                proteins, up to 45% of the dry matter, polyunsaturated fatty acids (PUFAs), such as EPA (eicosapentaenoic acid), up to 5% of the algae lipids, group B vitamins, vitamin B12 in particular, and vitamin A and the carotenoids.        
The prior art contains descriptions of numerous properties of extracts of the algae Porphyra and the compounds that they contain such as, for example:                antioxidant properties of a methanol extract (80%) of Porphyra tenera; antioxidant properties of extracts in various polar and apolar solvents of Porphyra yezoensis, of the methanol extract, in particular; antioxidant properties of an extract made with methanol (50%) and acetone; the presence of high concentrations of taurine and its derivatives, soluble in water-alcohol medium, known for its elicitor properties of chaperone proteins (HSP); the presence of derivatives of soluble sugars in water-alcohol medium such as floridoside (alpha-D-galactopyranosyl-(1-2)-glycerol) and its isomers which play an essential role in the osmotic regulation of cell medium subjected to notable hydric stresses; and the presence of porphyran, polysaccharide of the gars family, not extracted because it is not soluble in water-alcohol solutions having an alcohol content greater than 70% which have immunostimulant and antitumor properties.        